A good way to whiten your yellow teeth at home is by mixing some baking soda with a little water and making a toothpaste out of the baking soda and water and then brush your teeth at least 2 times per day for around a week.
After a week of brushing your teeth with baking soda and water toothpaste your teeth should begin to whiten.
You can also have a dentist whiten your teeth but that's expensive but they can really whiten your teeth fast.